Limelight’s documenation has provided two methods to wire the Limelight on the robot. It seems that both methods will need a port on the PDP , which means the motors can be used will be 15. So , l wonder whether the Limelight can be wired without using the port on the PDP?
I have been able to wire one to the vrm before but it’s not as nice as when it is wired to the pdp
It is recommended by limelight to not use a vrm. You can power in on a custom circuit that includes other low power devices though
I’m not sure what you mean by this. All electricity on the robot must be sourced from the PDP (with a few exceptions that don’t apply here). You could plug it in to a VRM, but not the one powering the radio, so you’ll have to use a pdp port anyway (don’t do this, just plug it in directly to the pdp).
This is just a limitation that comes with using a limelight or other similar device. If you have multiple, you can use a rev MPM or similar to have them all on the same pdp port.
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If you need the extra motors then a REV PDH might be what you’re looking for, as it contains a few extra slots compared the PDP.
We used a Rev POE cable that comes with the kop but that required us to get an adapter to connect the male ethernet end of the POE to the male end on the ethernet cable. Is there a better way to do this that we missed?
Don’t forget per R602 you could also use a secondary battery if you are really hurting for power slots for this this application.
We werent hurting for power, just didnt want to cram two more wires in the energy chain and up the back of the shooter
Same answer – you can put the battery on the turret.
External batteries are limited to 5v max output; the limelight takes 12v nominal and 6v appears to be the minimum needed to stay powered; the LEDs will start dimming at 7.5.
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“DC output: 12.0V; Max current: 0.6A”
What is the powerdraw of the limelight 2+? There was no defineitive answer on this thread: Limelight 2+ actual power consumption?
This is what we did in 2020. Battery power to the limelight, all mounted to the turret.
I wasn’t involved with the specifics of what Battery, but I believe we used a step converter like you linked.
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The Raspberry Pi CM4 io board datasheet recommends budgeting 9w for the compute module itself. That alone would put it over the 0.6 a output, without factoring the LEDs.
We’ve used these in the past, we just cut off the barrel connector and put ferrules on the bare wires:
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We didn’t have a free PDP port for part of the season and used a boost converter with a Limelight 2+ drawing off of the VRM’s 5V 2A output using one of these:
Our other option was to consider using a battery.
Before doing this, I asked Limelight support and Brandon said:
The current draw for LL2+ at 12V is 700mA. (8.4W)
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We don’t have PDH, and It is discontinued
You mean this PDH? It’s not discontinued, rather out of stock due to supply chain issues. I’d recommend getting one when it’s back in stock, as the extra slots and latch style WAGOs makes things much easier for you.
However, if you’re not able to give up a slot right now, I’ve personally had success with plugging it into 12V2A on the VRM, and although Limelight docs tell you not to I’m not sure of any inherent danger. I played around with Limelight on the VRM for a good 2 months without anything bad happening. If there’s some real technical reason why it’s a bad idea, even temporarily, to put it on VRM, then someone else can chip in.
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Can l wire a motor on rev MPM?
No. See R621:
R621 *Protect circuits with appropriate circuit breakers. Each branch circuit must be protected by 1 and only 1 circuit breaker or fuse on the PDP/PDH per Table 9-3. No other electrical load can be connected to the breaker or fuse supplying this circuit.
Emphasis mine.
You can only have 1 motor controller per breaker, and no other load can be connected to that breaker.
Also R625:
CUSTOM CIRCUITS shall not directly alter the power pathways between the ROBOT battery, PDP/PDH, motor controllers, relays (per R503-B), motors and actuators (per R501)…
The issue here is that if the OP has a VRM on the robot, it’s to power the radio, so you wouldn’t want to plug in the limelight to it anyway (disregarding the fact that that configuration wouldn’t be legal). In that case you’d have to add another VRM, which you could add if you havent used the second VRM/PCM slot on the PDP. (This is not a legal configuration) Otherwise, you end up having to use a breaker slot.
No technical reason for not powering the limelight off the VRM, the limelight isn’t likely to draw >2a. It’s just not recommended since the limelight has its own regulator that allows it to run off of Vbus.
TLDR; Save a breaker space for a limelight: that’s the only legal place to power it from if you have a PDP.
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What issues does that cause? It’s plugging into a different port on the VRM, so I wouldn’t think that you’d get any problems from that.